11alpha-hydroxy-3, 20-diketo-pregnenes and allopregnenes unsaturated in ring a and process



United States Patent 11a-HYDROXY-3,20-DIKETO-PREGNENES AND ALLOPREGNENES UNSATURATED IN RING A AND PROCESS Carl Djerassi, Birmingham, Micln, and George Rosenkranz, Mexico City, Mexico, assignors, by mesne assignments, to Syntex S. A., Mexico City, Mexico, a corporation of Mexico No Drawing. Application March 6, 1953, Serial No. 340,899

Claims priority, application Mexico March 7, 1952 9 Claims. (Cl. 260-39745) The present invention relates to novel cyclopentanophenanthrene derivatives and to a method for the preparation thereof.

More particularly, the present invention relates to ring A unsaturated compounds of the pregnene and allopregnene series having an llu-hydroxy group and 3 and 20- keto groups as well as to esters thereof.

In accordance with the present invention it has been discovered that allopregnan-l1ut-ol-3,20-dione and its esters may be converted into the novel A -allopregnen- 11a-01-3,20-di0116 and esters thereof and the corresponding A -isomers. In accordance with the present invention, there has been further discovered that the aforementioned starting materials may be converted into certain novel bromo compounds as well as other certain novel intermediates for the production of the final compounds referred to.

The novel final products of the present novel process just referred to have therapeutic homone activity, especially of the type characterizing the adrenal cortical steroids. Further since the lla-hydroxy group may be readily oxidized to the ll-keto group with chromic acid, they are also intermediates for the production of the corresponding ll-keto unsaturated compounds. All of these compounds can be hydrogenated to the known compound allopregnan-3,11,20-trione (Fieser and Fieser, Natural Products Related to Phenanthrene, page 421).

The following equations serve to illustrate the present invention:

In the above equations, R preferably represents an acyl group, i. e., the residue of an organic acid conventionally used for the esterification of steroid alcohols. More particularly, R represents the residue of a lower fatty acid such as acetic or propionic or the residue of an 3 aromatic acid such as benzoic. hydrogen.

In practicing the process above outlined, an ll-monoester of allopregnan-l la-ol-3,20-dione, prepared in accordance with our United States application, Serial No. 338,145 filed February 20, 1953, now Pat. No. 2,712,028 dissolved in a suitable solvent such as glacial acetic acid, is treated with either one or three molar equivalents of bromine in acetic acid in the presence of a catalytic amount of hydrogen bromide. If one molar equivalent of bromine is used the 2-bromo compound is formed, and if three molar equivalents, the 2,4,17-tribromo compound. Thereafter, these bromo derivatives are subjected to dehydrobromination by treatment with a dehydrobrominating agent, i. e., a tertiary amine, such as lutidine or collidine, or in the case of the 2-bromo compounds, by formation of the corresponding dinitrophenylhydrazone or semicarbazone which is thereafter subjected to cleavage with a suitable agent such as pyruvic acid. The tribromo compound may also be formed by treating the monobromo compound with two molar equivalents of bromine as indicated in the second equation. Thereafter conventional saponification gave the corresponding free compounds, i. e., n -allopregnen-l1u-ol-3,20-dione and A pregnatrien-l 1tZ-Ol-3,20-di0l'l6.

The following specific examples serve to illustrate, but are not intended to limit the present invention:

R may also represent Example I A solution of l g. of allopregnan-l1a-ol-3,20-dione acetate in 60 cc. of acetic acid containing three drops of at 4-normal solution of hydrogen bromide in" acetic acid was treated dropwise and under mechanical stirring with a solution of 1.05 molar equivalents of bromine in acetic acid. After the solution had completely decolorized, it

was diluted with water and the precipitate was filtered,

washed with water and air dried. The product was 2- bromo=allopregnan-11a-ol-3 ,20-dione=-acetate.

Example II A solution of 1 g. of the 2-bromo derivative obtained according-to Example I, in 7 cc. of gamma-collidine was refluxed for 45 minutes. The solutionwas cooled and the precipitate of collidine hydrobromide formed was filtered (its weight corresponded to 0.89 molar equivalents) and washed with ether. The filtrate was dilutedwith more ether and the solution was washed with dilute hydrochloric acid,',sodium carbonate solution and water; dried over sodium sulphate and evaporated to dryness. in order to purify the product, it was dissolved in a mixture of benzene-hexane and passed through a column with 3 g. of ethyl acetate washed alumina. Recrystallization from ethyl acetate yielded N-allopregnen-l1a-ol-3,20-dione acetate.

In the above experiment, gamma-collidinecan be substituted by 2,6-lutidinewith the same results.

Refiuxing the acetate for 1 hour with 1% ethanolic potassium hydroxide under atmosphere of nitrogen, followed by the usual work up, gave the free A -allopregnen- 1 1a-ol-3 ,20-dione.

Example III A solution of 1 g. of the 2-bromo compound obtained according to Example I, 0.8 g. of semicarbazide hydro- .chloride and'0.9 g. of sodium acetate trihydrate in 150 cc. of glacial'acetic acid was heated at 60 C. during 2 hours under atmosphere of nitrogen. After this time, 10 cc. of pyruvic acid, 3 g. of sodium acetate and 20 cc. of water were added and the mixture was heated 2 hours at 75 C. An additional a1nount 4 cc.) of pyruvic acid was added and the mixture was kept standing overnight. Next day itwas. dilutedwith much water and the precipitate was extracted with chloroform, washed with sodium bicarbonateand water, driedover sodium sulphate and evaporatedf to dryness, thus giving A -allopregnen-11u-ol- 3,20-dione acetate identical to the'one obtained according, to Example 11.

Example IV A solution of 2 g. of the Z-bromo derivative obtained according'to Example land 1.1 molar equivalents of 2,4- dinitrophenylhydrazine in 50 cc. of acetic acid was heated at 100 C. for 5 minutes, cooled and the crystalline"orange-dinitrophenylhydrazone formed was collected and w'ashedwith alcohol. 1' g. ofthis'compound was dissolved-in 50 cc. of chloroform and mixed with 75 cc. of"85%* hydrochloric acid and 6 cc. of a l-normal solution of hydrogen bromide in acetic acid. The mixture was heated'at60' C. for 3 hours under atmosphere of nitrogen and thendilutedwith'chloroform; The chloroform solutionwa's'washedwith' sodium'carbonate and water, dried over-sodium sulphate and evaporated to dryness. After one crystallization from ethyl acetate the residue gave A -allopregnen-1la-ol-3,20 dione acetate, identical to the one obtained according to Example H.

Example. V

'A solution of 2. g. of2 brorno allopregnan-1Idol-3,20-

dione acetate in acetic'acid containing 5 drops of. a 4- normal solution of hydrogen bromide in acetic acid, maintained at 25 C., Wastrea'ted with asolution. of'2 molar equivalents of bromine in acetic acid. After standing overnight, the solution was diluted with water and the precipitate formed was filtered, washed and recrystallized from chloroform to give 2,4,17--tribromo-allopregnan- 1l. x-ol-3,20-dione acetate.

The same product was obtained by treating 2 g. of allopregnan-l1a-ol-3,20-dione acetate, in solution in acetic acid containing l0drops of a 4-normal-solution of hydrogen. bromide-in acetic acid, with a solution of 3 molar equivalents of bromine in acetic acid andfollowing', the method described above.

Example VI A- solution of 2 g. of'the'tribromo derivative obtained according to Example V in 12 cc. of gamma-collidine was refluxed for 1 hour and after filtering. theprecipitate of collidine hydrobromide formed, the solution was diluted with ether and washed with dilute hydrochloric acid, sodium carbonate and water, dried over sodium sulphate and evaporated" to dryness. The residue was dissolved in the necessary amount of hexane and passed through a column with 15 g. of ethyl acetate washed alumina. Recrystallization from acetone-hexane yielded n pregnatrien-1lu-ol-3',20 dione. The same result was obtained when collidine was substituted by 2,6- lutidine.

Saponificationwith a 5% solution of potassium car bonatein alcohol, refluxing during one hour; gave the free N -pregnatriendlot ol-3,20-dione.

We claim:

1. A process for'the' production of the compound selected from the-class'consistingof n allopregnen-l'la-ol- 3,20-dione, lower fatty acid esters thereof, the benzoic acid ester thereof, A -pregnatrien-11a-ol-3,2O-dione, lower fatty acid esters thereofand the benzoic acid ester thereof which comprises treating a compound selected from the' class consisting of allopregnan-l1a-ol-3,20-dione, lower fatty acid esters thereof and the benzoic acid ester thereof with bromine to form the corresponding compound brominated at least in ring A and thereafter treating said brominated compound with a dehydrobrorninating agent.

2. The process of claim 1, wherein approximately one molar equivalent of bromine is used as the brominatingv agent and a n -cornpound is formed.

3. The process of claim 1, wherein approximately three molar equivalents of bromine are used as the brominating agent and a A -compound is formed.

4. The process of claim 1 wherein'the compound selected from the class consisting of allopregnan-l liar-ol- 3,20-dione and esters thereof is first treated with one References Cited in the file of this patent UNITED STATES PATENTS Marker Feb. 6, 1945 Murray et al. July 8, 1952 

5. A NEW COMPOUND SELECTED FROM THE CLASS CONSISTING OF $1-ALLOPREGNEN-11A-OL-3,20-DIONE, LOWER FATTY ACIDS ESTERS THEREOF, THE BENZOIC ACID ESTER THEREOF, $1,4,16-PREGNATRIEN11A-OL-3,20-DIONE, LOWER FATTY ACID ESTERS THEREOF AND THE BENZOIC ACID ESTER THEREOF. 